Re: open ports

["azeem ahmad" <azeem484@hotmail.com>]

i m also doing so but there is the problem of some programs that some times 
use dynamic ports like msn messenger uses dynamic ports for file transfer 
through it (i think so if it is wrong then tell me please) ad where the log 
will go and can i specify any file instead of the one default

Regards
Azeem


>From: Antony Stone <Antony@Soft-Solutions.co.uk>
>Reply-To: netfilter@lists.netfilter.org
>To: netfilter@lists.netfilter.org
>Subject: Re: open ports
>Date: Sun, 16 May 2004 10:43:06 +0100
>
>On Sunday 16 May 2004 10:22 am, azeem ahmad wrote:
>
> > hi all
> > i have a LAN environment. users from LAN connect to internet via my 
>linux
> > box. on this box iptables firewall runs. what ports should i open to 
>allow
> > users to get all the services like all chat rooms and yahoo, msn 
>messengers
> > and browsing http/ftp etc
>
>1. Start with the following ruleset
>
>iptables -P FORWARD DROP
>iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
>iptables -A FORWARD -j LOG
>
>2. Get one of your LAN machines to attempt a connection to something you 
>want
>to be allowed (eg: web borwsing).
>
>3. Look at the LOG entries to see what packets tried to get through the
>firewall (just before DROPped by the default policy).
>
>4. Add a rule, between the two rules given above, to allow that type of
>traffic (eg: for web browsing:
>iptables -I 2 FORWARD -i $intIF -p tcp --dport 80 -j ACCEPT)
>
>5. Read one of the networking tutorials from http://www.netfilter.org to 
>get a
>better understanding of what network protocols should always be allowed 
>(eg:
>both types of DNS), and how to find out what port numbers etc are used by 
>the
>services you want to allow through the system.
>
>Regards,
>
>Antony.
>
>--
>If you can't find an Open Source solution for it, then it isn't a real
>problem.
>
>                                                      Please reply to the 
>list;
>                                                            please don't CC 
>me.
>
>

_________________________________________________________________
The new MSN 8: advanced junk mail protection and 2 months FREE* 
http://join.msn.com/?page=features/junkmail